Gut Germs May Influence Success of Weight Loss Surgery

How many pounds someone loses after weight-loss surgery is linked to the types of germs they have in their gut, new research suggests.

The study found that higher levels of certain microbes — specifically those that produce methane — may translate to slightly less weight loss. These germs are known as methanogens.

“Our new study suggests that gastrointestinal colonization with methanogens makes it harder to lose weight after bariatric surgery,” lead investigator Dr. Ruchi Mathur said in an Endocrine Society news release.

The researchers reached their conclusions by studying the breath of more than 150 patients — 112 women and 44 men — who’d undergone weight loss surgery, also known as bariatric surgery, four to 12 months earlier. A person’s breath offers insight into the germs in his or her digestive system.

Thirteen of the patients tested positive for methane and hydrogen. On average, the decrease in their body-mass index — a measure of obesity — was slightly more than 20 percent compared to 23.5 percent for the other patients.

Mathur, director of the Diabetes Outpatient Treatment and Education Center at Cedars-Sinai, Los Angeles, said too many methane-producing germs could alter a person’s metabolism. But it may be possible to change a person’s gut germs through medication or diet.

“We believe such interventions will help these patients achieve their weight loss goals after bariatric surgery,” Mathur said.

The study was to be presented Thursday at the annual meeting of the Endocrine Society in San Diego. Studies released at meetings should be considered preliminary until they are published in a peer-reviewed medical journal.